After calling it quits with One Direction's Harry Styles, the new single star, 23, wore a dark plum taffeta Donna Karan Atelier gown with a sexy low back and dramatic train. To show off the backless style, Swift wore her hair up and accessorized with dangly earrings.

Swift's song "Safe & Sound," featured in The Hunger Games, earned a nomination for Best Original Song. "It's amazing to be nominated for Best Original Song. I'm just so thrilled to get to be here," she told E!'s Ryan Seacrest on the red carpet. "This is such a fancy night."

For a change, Swift got to write about something other than love life for the song. "Lionsgate Film came to us and said, 'We want you to write from Katniss' point of view' . . . My co-writers the Civil Wars and T-Bone Burnett were amazing," she explained. "We had this idea that we wanted the song to be about the empathy that goes into this film ." In a film with a lot of action and fighting, Swift added, "We wanted to highlight the fact that there's a lot of heart beneath all that.